Regeneration of Pyrolyzed Photoresist Film by Heat Treatment

A simple, time-, and cost-effective procedure is described for regenerating film-modified or deactivated pyrolyzed photoresist film (PPF) surfaces. Heating for 30 min at 545 ± 25 °C in argon at a flow rate of 1 L min(-1) removes covalently bound thin organic films, attached via electrografting from aryldiazonium salt solutions. The heat-treated surfaces exhibit improved electrochemical characteristics compared to those prior to modification and can be reused for solution-based electrochemical measurements and for electrografting. The same treatment reactivates PPF electrodes that have been deactivated by exposure to adsorbates from air or solution. X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and water contact angle measurements establish that the regeneration procedure does not lead to significant changes in oxygen content, roughness, or hydrophobicity of PPF surfaces. XPS measurements also confirm the complete removal of covalently attached organic films after heat treatment but reveal a specific interaction between grafted nitrophenyl films and PPF which results in a small amount of N incorporation in the surface.